The family of Oscar Pistorius have dismissed as fake a tweet saying he was thankful for prayers offered to his family and that of his slain girlfriend.

The South African athlete shot dead model and law graduate Reeva Steenkamp at his luxury home near Pretoria in the early hours of February 14.

He says he mistook Steenkamp for an intruder. He has been charged with premeditated murder and was released on bail on Friday.

The tweet was published on his brother Carl's account and reported as Oscar's first public reaction outside of court appearances since his arrest.

But the message, which read "Thank-you to every person that has prayed for both families, Osca", has now been removed, and the Pistorius family says Carl's Twitter account was hacked.

"It is most unfortunate that during this sensitive time, someone would choose to hack into Oscar Pistorius's older brother, Carl Pistorius's, Twitter handle," said family spokeswoman Janine Hills.

"Carl did not tweet this afternoon, out of respect to Oscar and Reeva."

Another spokeswoman said the Pistorius family is "very sensitive towards Reeva and her family and the tragic accident".

Hills said the family was cancelling its Twitter accounts.

Pistorius was freed on a record 1 million rand ($100,000) bail on Friday after eight days in custody and an emotionally charged, four-day bail hearing.

His lawyers successfully argued the Olympian, known as Blade Runner for his prosthetic running legs, was too famous to flee justice.

Family relieved

His family expressed "immense" relief at his release.

"We are extremely thankful that Oscar is now home," his uncle Arnold Pistorius said in a statement.

But the victim's father, Barry Steenkamp, told local media Pistorius would have to live with his conscience after the death.

"It doesn't matter how much money he has and how good his legal team is, he will have to live with his conscience if he allows his legal team to tell lies on his behalf," Barry Steenkamp told Beeld, an Afrikaans newspaper.

"But if he is telling the truth then maybe I can forgive him one day. If it didn't happen the way he said it did, he must suffer, and he will suffer ... only he knows."

Reeva's mother, June Steenkamp, told Beeld she had "cried out all my tears".

"I just want to finish mourning my daughter. I will have to get used to life without her," she said.

Pistorius's family sent flowers and a card to the Steenkamp family, but "what does that mean?" she asked, before adding: "Nothing."

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